1. Field of the Invention
The present invention relates to a method and system for handoff in a mobile communication system supporting a mobile IP (Internet Protocol), and more particularly to a method and system for efficient handoff in a mobile communication system using a proxy mobile IP.
2. Description of the Related Art
In recent years, IP-based communication networks have remarkably developed by virtue of the rapid progress in Internet technology. In such IP-based communication networks, service data is transmitted/received using an allocated IP address. Network address systems for transmitting data to a mobile station, that is, a mobile node, have also been proposed even in mobile communication systems, and among them is mobile IP technology which is a typical scheme for allocating an IP address to a mobile node. The mobile IP technology has been proposed to provide seamless communication even during handoff, as more users use a mobile node due to the rapid progress in mobile communication systems and an increase in wireless LAN services.
The mobile IP technology is under much discussion in the IETF (Internet Engineering Task Force), one of many standardization associations. The version of the mobile IP technology has recently evolved from mobile IPv4 to mobile IPv6. Similarly, commonly used wired IP-based communication networks were started based on IPv4, but are evolving into IPv6 that is a more advanced type for overcoming IP resource limitation, accommodating increased users and providing various services. The major feature of IPv6 is an increase in the length of an IP address (from 32 bits to 128 bits), which makes it possible to accommodate more subscribers.
The mobile IP technology is problematic in that its protocol itself has too much overhead for use in a mobile communication system. Thus, in order to reduce such overhead, the 3rd Generation Partnership Project (3GPP2), one of the standardization associations for mobile communication technology, has proposed proxy mobile IP technology that is currently under standardization. Thereupon, research is being actively conducted to improve the performance of a mobile communication system by using the proxy mobile IP, and particularly the 3GPP2 is now discussing the standards of using the proxy mobile IP for improving handoff performance.
When the proxy mobile IP is used during handoff, there is an advantage in that a handoff delay can be reduced as compared to the conventional mobile IP. However, a mobile node in a wireless environment supporting the proxy mobile IP must perform operations for an IP protocol independently of the wireless environment irrespective of whether it supports a conventional simple IP or the mobile IP. Thus, there is a need for support of a protocol in order to efficiently support handoff in a mobile communication system supporting the proxy mobile IP.